Super Street Network

Due to the EU’s Global Data Protection Regulation, our website is currently unavailable to visitors from most European countries. We apologize for this inconvenience and encourage you to visit www.motortrend.com for the latest on new cars, car reviews and news, concept cars and auto show coverage, awards and much more.MOTORTREND.COM

'15 GT3RS vs '15 GT4 - Which is the Ultimate Driver’s Porsche?

Is the engineer’s 911 better than the enthusiast’s Cayman?

This isn't a comparison of two cars. This isn't a comparison of mid-engine and rear-engine. It isn't even a comparison of manual and dual-clutch transmissions. This is a comparison of ideologies—a comparison of two systems of belief. This is religion. Those torn between an allegiance to Star Wars and Star Trek know the gravity of the situation. I will attempt to be your shaman, your spirit guide as we discover our true feelings on the nature of what makes a great car.

The '15 GT3RS is the clearest distillation of Porsche's racing heritage and knowledge, and arguably the best 911 ever built. The '15 Cayman GT4 is the most driver-focused mid-engine car, and some would say, the most pure Porsche currently built. I drove both of them back-to-back at Road Atlanta in some rather varied conditions to determine if the ultimate engineering triumph outshines a project of utter passion.

If this were merely about performance or lap times, the GT3RS wins, hands-down, no comparison, end of story, cue the art director and lunch! That isn't what we're talking about; this isn't the comments section of Facebook; this is far more critical than just numbers. We are talking about the very essence of being a driving enthusiast. The very philosophical debate of: Are heritage, tradition, and experience more important than advancement and all-out performance?

The Cayman GT4 is the car Porschephiles have asked for, for years. It's a mid-engine, high-horsepower, manual transmission, no-holds-barred driver's car. This is the car that Internet and bench racing rumblings have said, that if built, will finally replace the 911. From the launch of the very first Boxster in 1997, fans of the "lesser-sportscar" have been spreading rumors of the insidious plan within the halls of Zuffenhausen to keep the mid-engine cars slower than the venerable 911 to prevent a mid-mounted mutiny.

The advantages of the mid-engine layout are obvious, at least on paper. The centralized weight, polar-moment of inertia in geek-speak, means the car will naturally rotate quicker. The rear-engine layout not only means slower rotation, but the weight hanging out the back means that once it starts rotating, it is more difficult to stop, resulting in the 911's legendary oversteer. Legendary is probably the best term, because like Paul Bunyan, the stories seem to grow bigger and wilder every year. I won't dispute the fact that 911 drivers have backed into more than their share of roadside obstacles, but I have a feeling many of those drivers would have broadsided those obstacles had they been in front or mid-engine cars. There is, however, an advantage to the rear-engine layout, namely better grip during acceleration and braking. Remember slow in, fast out? Not only does it apply to spicy foods, but it's also the longtime mantra of effective 911 drivers.

I said we wouldn't get hung up on numbers and we won't get hung up on performance numbers, but let's look at the ones that matter. First, size—the GT3RS is 179 inches long, 74 inches wide, and 51 inches tall. The Cayman is an inch shorter in height, 2 and 1/2 inches narrower, and a little more than 4 inches shorter in length, but wait, there's a more interesting part. While the Cayman is substantially shorter in overall length, its wheelbase is just over an inch longer at 97.8 inches. The GT3RS also has an inch greater rear track width and 2 inches in front track width.

The GT4 is just over 200 pounds lighter than the 3,243-pound GT3RS but again, that is a very small part of the picture. The GT4 carries 56 percent of its total weight on the rear axle while the rear-engine GT3RS carries 61 percent. And while the Cayman wears an impressive 295/30-20 on the rear, the GT3RS has a whopping 325/30-21 out back, which happens to be the same size found on the back of the 918. Not only is the rear tire more than an inch wider than the Cayman's, the actual tread width is 2.5 inches wider and the tire is nearly 2 inches taller. It has a lot of sidewall and looks and performs better for it.

Lastly, let's talk about power—not just power, but how it's made. Obviously, both cars offer a naturally aspirated flat-six. I say obviously, but this might be the last time we see them. The GT4 is 3.8 liters, while the RS is an even 4.0 liters. The GT4 makes peak torque at 4,750 rpm and peak power at 7,400, just 200 short of redline. The RS, wait for it, makes peak torque at 6,250 rpm and, are you ready, peak power at 8,250 rpm. Did I mention it will happily spin all the way to 8,800 rpm before the rev limiter stops you? Every individual horsepower in the GT4 is required to accelerate 7.9 pounds of mass, while the lucky horses in the RS are only assigned 6.6 pounds each. It's pretty easy to figure out which is the faster car.

Again, I need to emphasize, this isn't about numbers but about the spirituality of driving. So get on with it you say. First, and maybe most importantly, the GT4 is a smaller and tighter package even from 50 feet away. The RS looks like a warhorse and the GT4 a thoroughbred. Sitting in the car gives the same impression; the RS cabin is a larger place with more room in just about all directions, especially in the area where the rear seats live on other 911s. The GT4 wraps around the driver and you almost wear the car. While the GT3RS feels just like sitting in a Cup Car, you can kind of trick yourself into thinking your Cayman is that 956 you've fantasized about since you were 12 years old.

It would have to be something of the 956 vintage since the clutch pedal and H-pattern six-speed didn't make it far past that era of racing. There is some irony in the fact that the manual transmission is all but extinct, and this might be the best one I have ever experienced. The shifts are a mix of mechanical clinks linked by velvety slips between gears. The throws can only be described as ideal; any longer and it wouldn't fit the race-car-like mood, and any shorter would be a very well-engineered toggle switch. The clutch has actual feel. This isn't one of the many holdouts in the manual world that have polished out all the mechanical feedback in an effort to make them more attractive to modern buyers who are accustomed to all the feedback of an iPhone. The art, science, and fantasy of rowing through the GT4's gears is as tactile as dialing a rotary phone (ask your parents).

The front suspension of the GT4 was lifted straight from a 911 GT3 with the two-piece lower control arms, adjustable antiroll bars, and even the brakes. It is as accurate here as on its original home, maybe more so with the GT4's weight balance. The conditions at Road Atlanta ranged from almost completely dry to "I'm pretty sure there's a track under all this water." In all but the wettest of conditions, the front gives good feedback; when it stopped, that meant there was no feedback to be had since the tires had turned to flat-bottom boats. It still doesn't shake and kick like an old air-cooled car's steering—go buy a 914 if you want that—but you still know when it's loading up, when it's going to let go, and if you can push harder, and ultimately that's all that matters.

When you do push too hard, and the car begs for it on track, it'll respond with a slower breakaway than maybe you've come to expect from low moment of inertia cars, especially on Cup tires and maybe even more so, with downforce. The GT4 is one of those rare cars with very high limits that feels like you can just skate around the outside of the friction circle. The initial instinct of the car is to understeer, but slightly. Sneak up to the limits on-throttle at mid-corner and you can get both ends to let go simultaneously.

There are precious few moments in life when everything melds into place; you, the car, the universe, and a complete feeling of Zen encompass the car like a warp bubble. Time slows, you're more aware of everything, your senses as acute as raw nerves, yet you're body is operating purely on instinct. The great Ayrton Senna claimed he would spend entire races in that meditative state, said he would experience God. If I'm lucky, I can experience that for a few fleeting seconds, in small sections of corners during an eight-hour track day. I hear Ben Kenobi. In the GT4, I felt it several times, for corners strung together. I should point out that I almost Zen'd the car off the track at one point during a torrential downpour. Ben wasn't pleased.

The GT4 puts its power to the ground beautifully and will let you feed it in as you desire. If the back starts to come around, you can ride it out. Don't get me wrong, the car is challenging and I feel like I could do a track day a month for a few years and still find time, but I also feel like mastery of the GT4 is within the grasp of mere mortals like myself.

The GT3RS is a racer's race car. It is what I believe to be the closest thing to an actual GT race car at a dealership today. With that in mind, it is slightly intimidating as a driver, yet utterly fascinating to the technically minded. I've spent a decent amount of time in the RS on public roads in Germany. While it is perfectly capable as a daily driver, using it for commuting is like using a single malt whiskey for Irish coffee.

The GT3RS has more energy sitting still than the GT4 has cruising at part-throttle. Idling in the pits, the RS radiates mechanical purpose. The GT4 says, "Let's go drive." The RS grumbles, "I'm going to crush some lap times, if you're driver enough." It's powerful, it's demanding, and it's imposing—and you know this before you've started moving. There are two pedals and two steering wheel–mounted paddles in front of you, just like any modern race car. For a driver, this is where you work, not play. The full bucket seats are good, really good for something the DOT will sign off on, but if this were my car, it would have FIA-approved racing buckets and harnesses in addition to a rollcage.

The first time I drove this car was in Germany on a track designed by Walter Röhrl to thrill experienced drivers and punish those ill equipped. It was a beautiful, sunny day with a light, cool breeze. At Road Atlanta, the track is more straightforward but the weather seems intent to do the punishing. The Michelin Pilot Sport Cup 2 tires are as good in the wet as something this good in the dry can be. Being from sunny Southern California, racing greats Hurley Haywood and David Donohue give me hints and tips on conserving heat in the tires and finding the driest areas of the tracks.

Right before heading out, I'm warned to stay off the curbs and in slow corners, don't commit to the throttle until the front tires are pointed nearly straight. First lap, Turn 3, curbs—check. Easy on the gas, Turn 7—check; lessons learned. Or at least, demonstrated. I stay away from the curbs the rest of the day, but I keep having trouble with the light right foot. I had noticed it in the dry as well. Porsche GT cars have a pretty decent amount of adjustability built in: individual ride heights for corner balancing, antiroll bars, and front and rear downforce. In the back, you can adjust the wing's angle of attack. In the front, you can pull the grilles out of the fender vents, increasing flow. For whatever reason, Porsche seems to like to set up these cars to oversteer on-throttle, a lot. That isn't usually a bad thing, if it's done in a controlled, moderate fashion. The GT3RS, however, lives up to the old 911 legend.

I find myself exiting Second and Third gear corners in a gear higher than what I normally would in an effort to self-regulate torque. The naturally aspirated engine delivers power in a way that turbocharged cars have yet to master; yet even with the subtlety of throttle, I still need to keep the overeager engine reined in on the wet asphalt. Unlike the Cayman, once the rear tires of the RS let go and the rear starts to rotate, it isn't something you can ride out. It took multiple laps for me to finally concede. Sadly, the laws of physics seem to be more stubborn even than me.

Once the car steps out, my only option is to catch it and get the tires hooked back up before getting into the throttle. There is no riding on the edge. There is no driving your hip to the exit. Once the car is settled, however, acceleration is as race-car-like as the soundtrack. The lack of rear-weight transfer means that once the rear tires are hooked up, it doesn't lift the front, creating on-throttle understeer. Once I come to terms with the driving style required for the way the RS is set up coupled with the conditions, I can begin to sink my teeth into the science.

The RS develops race car levels of downforce; well 760 pounds of downforce, which I am told, is roughly 80 percent of what Cup Cars are capable of. Road Atlanta is an ideal spot for experiencing atmospherically augmented grip. Exiting turn 7 is an exercise in self-control. I would normally use Second gear. It's slightly more than a 90-degree turn, making it oh so tempting to overcook. Corners like this are my nemesis in powerful rear-wheel-drive cars. In front- or all-wheel-drive cars, I would try and rotate the car with trail braking, late apex, and power out, working to keep the rotation going all the way out. The RS doesn't work like that. If I get it rotating, I probably can't get it back. I don't trail brake or try to free up the back end, but the RS does use its rear-wheel steering to get the car turned in. In the dry, the car could better use its torque-vectoring differential; in the wet, it's my torque-limiting right foot.

In Third gear, once straight and hooked up, the RS accelerates down the back straight with the authority of one of its all-wheel-drive siblings. Road Atlanta's back straight is not, in fact, straight. Turn 8 is a gentle left and then Turn 9 is a bit more aggressive and to the right, but made more interesting by cresting and falling away at the exit. Even in the wet, at speeds north of 125 mph (I stop watching the speedometer at that point), the car feels planted in a way the GT4 doesn't. In the dry, I'm confident it would be even more in favor of the RS as speeds would be higher and the RS's tires would be even more effective. The end of the back straight really tells the story. The track drops away even faster as you squeeze into the brakes, the rear-engine and high-downforce RS burns-off speed easier than just about any other road car. The old cliché of races are won in braking zones is an old cliché for a reason. I've changed my mind, the RS doesn't so much as trick you into thinking you're in a Cup Car but reminds you that you are basically some leather and carpet away from one.

I expected the RS to feel slightly over-stiff when compared to the GT4 because of the need to compensate for the downforce at speed, but that isn't the case. If anything, the GT4 feels a little too active at times, and this is from a guy who constantly praises soft cars. Turns 10A and 10B are two quick flicks, left then right, and although the GT4 is more eager to change directions and maybe more fun, the RS is better at it, with an asterisks. I feel like I can hustle the GT4 through here with a flick to change directions like a skier digging in one foot and then hopping and pivoting to the other. With the GT3RS, I feel like I'm trying to keep the car sitting on the back end, swinging the barrel of a cannon from one direction to the other before firing it up the hill.

I wouldn't call the GT4 a momentum car like the lower powered Caymans, but it does feel like it just wants to be driven in long arcs flowing one to another around the track. The RS wants to maximize speed everywhere possible. Really use the engine and braking power in straight lines and the downforce in turns. Just like race cars, it's meant to get around the track as fast as possible, but maybe not in a way that feels the best to the driver.

I have a feeling the car could be driven differently if you were to spend a few days at the track dedicated to setting up the suspension to be a little more driver friendly, or should I say more amateur friendly. I spend a lot of time on the track; I'm on a racetrack at least once a month and driving at the test track at least twice a month. I have had hours of training from some of the best. With that said, I will freely admit that I am no pro and don't possess anywhere near that level of ability; the level of ability required to really exploit a car like the GT3RS. Is it still enjoyable? Well, I would compare it to deep-fried cheese served in a gold basket lined with money. There is a catch; while I feel like I could master the GT4 with enough time, I don't think I would ever be able to get the full potential out of the GT3RS, and I don't know if that's a good or bad thing.

As an enthusiast, can you be happy knowing you will never be able to live up to a car's potential? Is that something that would enter into your thought process when deciding between two cars like this? The engineering and technology used in the GT3RS have taken some of the driver's personality out of the equation. There is only one way to drive the car fast. The GT4 could be driven a few different ways, one still might be faster than the other, but it wouldn't necessarily punish you for it.

In a perfect world, I would have both. A Porsche representative once told me I would probably be shocked, I would describe it as depressed, as to how many customers do own both. The salt in the wound is that not only do most of them own both a GT3RS and a GT4, but apparently these are the track toys that accompany a 918 Hybrid, ya know, for Earth-friendly commuting.